added updated version of simdmathlibrary-1.0.1
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ejcoumans
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Extras/simdmathlibrary/spu/simdmath/exp2f4.h
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Extras/simdmathlibrary/spu/simdmath/exp2f4.h
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/* exp2f4 -
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Copyright (C) 2006, 2007 Sony Computer Entertainment Inc.
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All rights reserved.
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Redistribution and use in source and binary forms,
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with or without modification, are permitted provided that the
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following conditions are met:
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* Redistributions of source code must retain the above copyright
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notice, this list of conditions and the following disclaimer.
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* Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in the
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documentation and/or other materials provided with the distribution.
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* Neither the name of the Sony Computer Entertainment Inc nor the names
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of its contributors may be used to endorse or promote products derived
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from this software without specific prior written permission.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef ___SIMD_MATH_EXP2F4_H___
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#define ___SIMD_MATH_EXP2F4_H___
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#include <simdmath.h>
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#include <spu_intrinsics.h>
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/*
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* FUNCTION
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* vec_float4 _exp2_v(vec_float4 x)
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*
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* DESCRIPTION
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* _exp2_v computes 2 raised to the input vector x. Computation is
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* performed by observing the 2^(a+b) = 2^a * 2^b.
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* We decompose x into a and b (above) by letting.
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* a = ceil(x), b = x - a;
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*
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* 2^a is easilty computed by placing a into the exponent
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* or a floating point number whose mantissa is all zeros.
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*
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* 2^b is computed using the following polynomial approximation.
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* (C. Hastings, Jr, 1955).
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*
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* __7__
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* \
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* \
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* 2^(-x) = / Ci*x^i
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* /____
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* i=1
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*
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* for x in the range 0.0 to 1.0
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*
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* C0 = 1.0
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* C1 = -0.9999999995
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* C2 = 0.4999999206
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* C3 = -0.1666653019
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* C4 = 0.0416573475
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* C5 = -0.0083013598
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* C6 = 0.0013298820
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* C7 = -0.0001413161
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*
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* This function does not handle out of range conditions. It
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* assumes that x is in the range (-128.0, 127.0]. Values outside
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* this range will produce undefined results.
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*/
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#define __EXP2F_LN2 0.69314718055995f /* ln(2) */
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static inline vector float
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_exp2f4 (vector float x)
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{
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vec_int4 ix;
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vec_uint4 overflow, underflow;
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vec_float4 frac, frac2, frac4;
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vec_float4 exp_int, exp_frac;
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vec_float4 result;
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vec_float4 hi, lo;
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vec_float4 bias;
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/* Break in the input x into two parts ceil(x), x - ceil(x).
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*/
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bias = (vec_float4)(spu_rlmaska((vec_int4)(x), -31));
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bias = (vec_float4)(spu_andc(spu_splats(0x3F7FFFFFu), (vec_uint4)bias));
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ix = spu_convts(spu_add(x, bias), 0);
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frac = spu_sub(spu_convtf(ix, 0), x);
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frac = spu_mul(frac, spu_splats(__EXP2F_LN2));
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// !!! HRD Changing weird un-understandable and incorrect overflow handling code
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//overflow = spu_sel((vec_uint4)spu_splats(0x7FFFFFFF), (vec_uint4)x, (vec_uchar16)spu_splats(0x80000000));
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overflow = spu_cmpgt(x, (vec_float4)spu_splats(0x4300FFFFu)); // !!! Biggest possible exponent to fit in range.
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underflow = spu_cmpgt(spu_splats(-126.0f), x);
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//exp_int = (vec_float4)(spu_sl(spu_add(ix, 127), 23)); // !!! HRD <- changing this to correct for
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// !!! overflow (x >= 127.999999f)
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exp_int = (vec_float4)(spu_sl(spu_add(ix, 126), 23)); // !!! HRD <- add with saturation
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exp_int = spu_add(exp_int, exp_int); // !!! HRD
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/* Instruction counts can be reduced if the polynomial was
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* computed entirely from nested (dependent) fma's. However,
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* to reduce the number of pipeline stalls, the polygon is evaluated
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* in two halves (hi amd lo).
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*/
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frac2 = spu_mul(frac, frac);
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frac4 = spu_mul(frac2, frac2);
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hi = spu_madd(frac, spu_splats(-0.0001413161f), spu_splats(0.0013298820f));
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hi = spu_madd(frac, hi, spu_splats(-0.0083013598f));
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hi = spu_madd(frac, hi, spu_splats(0.0416573475f));
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lo = spu_madd(frac, spu_splats(-0.1666653019f), spu_splats(0.4999999206f));
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lo = spu_madd(frac, lo, spu_splats(-0.9999999995f));
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lo = spu_madd(frac, lo, spu_splats(1.0f));
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exp_frac = spu_madd(frac4, hi, lo);
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ix = spu_add(ix, spu_rlmask((vec_int4)(exp_frac), -23));
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result = spu_mul(exp_frac, exp_int);
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/* Handle overflow */
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result = spu_sel(result, (vec_float4)spu_splats(0x7FFFFFFF), overflow);
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result = spu_sel(result, (vec_float4)spu_splats(0), underflow);
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//result = spu_sel(result, (vec_float4)(overflow), spu_cmpgt((vec_uint4)(ix), 255));
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return (result);
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}
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#endif
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